Postcard

The agency is hired by a television weather forecaster they nickname Weatherman to find out who is sending him mysterious postcards.1 For a while, the agency is at a loss as to who the person (Postcard) could be until Robin follows a hunch that takes her to the National Portrait Gallery.Barclay takes over the case and confirms that Robin’s hunch was right.3 

“’Bloody well done,’ Strike told Barclay.
‘It’s Robin’s win,’ said Barclay. ‘She made the pass. I jus’ tapped it in.’” 4

1: Troubled Blood, Chapter 7
2: Troubled Blood, Chapter 16
3, 4: Troubled Blood, Chapter 39